Importation of mass production of building elements with standardization are vital way for environment-friendly architectural planning, which it makes the lifespan of a building longer than normal with easier maintenance and remodeling. The advantage might be magnified here in Korea since typical types of apartment house are dominated in our construction market. For the purpose, a series of pre-manufactured window systems is one of the optimal elements to be prototype building modules. In the design process of the system windows, lots of consideration should be involved and they include aesthetics, thermal performance, noise reduction, airtightness, and so forth. A real survey on the ready-made window systems has been performed and its optical issue related to luminous peculiarity is what is of major interest in this study. In addition, technical review on more advanced window products and their adaptable potential for the integration with fundamental architectural design elements were carried out.